C. elegans XMAP215/ZYG-9 and TACC/TAC-1 act at multiple times during oocyte meiotic spindle assembly and promote both spindle pole coalescence and stability.
C. elegans XMAP215/ZYG-9 and TACC/TAC-1 act at multiple times during oocyte meiotic spindle assembly and promote both spindle pole coalescence and stability.
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DOI：
10.1371/journal.pgen.1010363
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发表时间：
2023-01
期刊：
影响因子：
4.5
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中科院分区：
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--
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在卵母细胞减数分裂过程中，在多个动物门中需要微管稳定性的保守的双组分XMAP 215/TACC调节剂用于无中心体纺锤体组装。In C. elegans、XMAP 215/zyg-9和TACC/tac-1突变体卵母细胞在减数分裂I早期表现出多个且难以区分的卵母细胞纺锤体组装缺陷。为了确定这些缺陷是否代表一个或多个早期要求，以及额外的后期和间接后果，或者多个时间上不同的和更直接的要求，我们使用了活细胞成像和快速作用的温度敏感的zyg-9和tac-1等位基因，以高时间分辨率来解剖它们的要求。温度升高和降低实验表明，ZYG-9/TAC-1复合物在整个卵母细胞减数分裂过程中具有多个时间上不同和可分离的要求。首先，我们表明，在前中期ZYG-9和TAC-1促进合并成一个双极结构的早期极焦点，稳定极焦点，因为他们的增长和限制他们的增长速度，这些要求是独立的早期缺陷微管组织时发生核膜破裂。第二，在中期，ZYG-9和TAC-1通过抑制异位极的形成来维持纺锤体双极性。第三，我们表明，ZYG-9和TAC-1也需要在减数分裂II纺锤体组装，独立于他们的减数分裂I的要求。中期极稳定性的要求似乎是重要的维持染色体的congression，我们讨论了如何负调控微管稳定性ZYG-9/TAC-1在卵母细胞减数分裂细胞可能占纺锤体极聚结和稳定性的缺陷。当大多数动物细胞分裂时，被称为中心体的大的多蛋白复合物成核，并将被称为微管的蛋白丝组织成一个动态的双极结构，称为纺锤体，它将复制的基因组平均分配给两个子细胞。然而，雌性卵母细胞缺乏中心体，但仍然组装双极纺锤体来分离染色体。利用线虫C. elegans作为一个模型系统，并利用快速作用的温度敏感性突变，迅速激活或重新激活蛋白质后，温度上升或下降，分别，我们表明，一个复杂的两个调控微管稳定性，称为ZYG-9和TAC-1，在无中心体卵母细胞纺锤体组装有多个和可分离的要求。这些要求包括促进早期极灶合并成双极结构，以及随后维持极稳定性，这两者对于正确的染色体分离都是必不可少的。此外，卵母细胞经历两次连续的细胞分裂以产生具有单拷贝基因组的卵，并且我们表明ZYG-9和TAC-1是在这些减数分裂细胞分裂的第一次和第二次期间极聚结所需的。我们的研究结果提供了一个高分辨率的视图，这些广泛保守的微管稳定性调节剂在无核小体卵母细胞纺锤体组装的独特和可分离的时间要求。
The conserved two-component XMAP215/TACC modulator of microtubule stability is required in multiple animal phyla for acentrosomal spindle assembly during oocyte meiotic cell division. In C. elegans, XMAP215/zyg-9 and TACC/tac-1 mutant oocytes exhibit multiple and indistinguishable oocyte spindle assembly defects beginning early in meiosis I. To determine if these defects represent one or more early requirements with additional later and indirect consequences, or multiple temporally distinct and more direct requirements, we have used live cell imaging and fast-acting temperature-sensitive zyg-9 and tac-1 alleles to dissect their requirements at high temporal resolution. Temperature upshift and downshift experiments indicate that the ZYG-9/TAC-1 complex has multiple temporally distinct and separable requirements throughout oocyte meiotic cell division. First, we show that during prometaphase ZYG-9 and TAC-1 promote the coalescence of early pole foci into a bipolar structure, stabilizing pole foci as they grow and limiting their growth rate, with these requirements being independent of an earlier defect in microtubule organization that occurs upon nuclear envelope breakdown. Second, during metaphase, ZYG-9 and TAC-1 maintain spindle bipolarity by suppressing ectopic pole formation. Third, we show that ZYG-9 and TAC-1 also are required for spindle assembly during meiosis II, independently of their meiosis I requirements. The metaphase pole stability requirement appears to be important for maintaining chromosome congression, and we discuss how negative regulation of microtubule stability by ZYG-9/TAC-1 during oocyte meiotic cell division might account for the observed defects in spindle pole coalescence and stability. When most animal cells divide, large multiprotein complexes, called centrosomes, nucleate and organize protein filaments, called microtubules, into a dynamic bipolar structure called the spindle that equally partitions the duplicated genome between two daughter cells. However, female oocytes lack centrosomes but still assemble bipolar spindles that separate chromosomes. Using the nematode C. elegans as a model system, and taking advantage of fast-acting temperature-sensitive mutations that rapidly inactivate or reactivate proteins upon temperature upshifts or downshifts, respectively, we show that a complex of two regulators of microtubule stability, called ZYG-9 and TAC-1, has multiple and separable requirements during acentrosomal oocyte spindle assembly. These requirements include promoting the coalescence of early pole foci into a bipolar structure, and the subsequent maintenance of pole stability, both of which are essential for proper chromosome separation. Furthermore, oocytes undergo two consecutive cell divisions to produce an egg with a single copy of the genome, and we show that ZYG-9 and TAC-1 are required for pole coalescence during both the first and second of these meiotic cell divisions. Our findings provide a high resolution view of the distinct and separable temporal requirements for these widely conserved regulators of microtubule stability during acentrosomal oocyte spindle assembly.
影响因子：
4.5
作者：
Davis-Roca AC;Divekar NS;Ng RK;Wignall SM
通讯作者：
Wignall SM